Retention strap assembly for a buoyancy module in a riser system

ABSTRACT

A retention strap assembly for a buoyancy module in a riser system, the retention strap assembly comprising: an elongate strap member comprising connection points at opposite ends, the strap member configured to wrap around the buoyancy module; a buckle member comprising connection formations configured to receive the connection points of the strap member, wherein the buckle member further comprises a tensioner configured to tension the strap member, the buckle member being configured to tension and hold the strap member around the buoyancy module; and a plurality of attachment formations spaced along a length of the strap member, each attachment formation comprising an attachment point configured for attachment to auxiliary riser equipment. The connection points of the strap member may be provided by ends of the strap member being looped or folded over. The strap member may comprise at least two overlapping layers.

FIELD OF INVENTION

This invention relates to deep- and ultra-deep-water drilling and oil field development. Specifically, this invention relates to a retention strap assembly for a buoyancy module in a riser system.

BACKGROUND OF INVENTION

An offshore riser system includes a riser string comprising a series of riser joints interconnected end-to-end. The riser string extends from a drilling rig (at a top end) to a wellhead on the ocean floor (at a bottom end). Running along much of the riser string are buoyancy modules which are mounted to the riser string in order to provide uplift to the riser string to reduce the aggregate weight thereof, as well as to ensure plumbness of the riser string.

The buoyancy modules are typically retained on individual riser joints using either threaded bolts, or straps and buckles which also are coupled through the use of threaded bolts. Such threaded bolts can be time-consuming to fit and can cause damage to the buoyancy module with repeated use.

The riser string is assembled by successively connecting and then lowering joint after joint of riser into the water, until the wellhead located on the sea bottom is reached. During the process of so being run, and after passing through the drill floor, the riser joints are often fitted with auxiliary equipment such as MUX clamps for the fitment of multiplexing (MUX) cabling and strakes or fairings for the reduction of vortex induced vibration (VIV) or drag. Less common but still significant or likely future fitments include riser monitoring equipment which are appended to the outer dimension of the riser joint.

The fitment of this auxiliary equipment takes place during a critical time, as it risks causing a bottleneck in the running of the riser joints and comes at significant cost to the drill rig operator. Similarly, though during less time-sensitive operations, the buoyancy module itself must be removed and changed out, repaired or serviced. This is often done in field service locations and thus comes at significant cost to the drill rig owner.

The Applicant wishes to address these drawbacks. The Applicant desires an assembly both to increase the rate at which the buoyancy modules can be fitted, removed and re-fitted to and from the riser joint during maintenance, and to increase the rate at which auxiliary equipment can be fitted to the riser joint assembly.

SUMMARY OF INVENTION

A retention strap assembly for a buoyancy module in a riser system, the retention strap assembly comprising:

-   -   an elongate strap member comprising connection points at         opposite ends, the strap member configured to wrap around the         buoyancy module;     -   a buckle member comprising connection formations configured to         receive the connection points of the strap member, wherein the         buckle member further comprises a tensioner configured to         tension the strap member, the buckle member being configured to         tension and hold the strap member around the buoyancy module;         and     -   a plurality of attachment formations spaced along a length of         the strap member, each attachment formation comprising an         attachment point configured for attachment to auxiliary riser         equipment.

The connection points of the strap member may be provided by ends of the strap member being looped or folded over.

The strap member may comprise at least two overlapping layers. The overlapping layers may comprise a single continuous strap, folded over itself, or plural strap parts, arranged one above the other.

The buckle member may comprise a buckle housing to which the tensioner is mounted. The tensioner may be rotatably or pivotally mounted to the buckle housing. The buckle member may comprise two connection formations. One connection formation may be provided on the buckle housing and the other connection formation may be provided on the tensioner. The tensioner may be fixable relative to the buckle housing, e.g., using a mechanical fastener.

The connection formations may comprise crosspieces or transverse supports and/or a solid body (e.g., bars or rods) around which the strap member may be guided or wrapped. The transverse supports may be removably attached to the buckle member. The transverse supports may be removably attached by mechanical fasteners, e.g., nuts or screws. In use, the transverse supports may be removed to connect or disconnect the strap member, and then fastened in place so that the strap member cannot be removed without detaching the support members. Neither the strap member nor the buckle member may be attached to the buoyancy module by mechanical fasteners.

The tensioner may comprise a lever member. The lever member may be an over centre lever. The lever member may include one of the connection formations and, via a levering action about its fulcrum, may be configured to tension the strap member when its connection point is connected to the connection formation of the lever member. The lever member may embody a class 1 or class 2 lever. Once in its tensioned position, the lever member will be secondarily retained in place through the use of mechanical fastener.

The strap member may be of a polymer, e.g., plastic or rubber, manufactured to include Kevlar strands. The buckle member may be of metal, e.g., steel. The attachment formations may be of metal, e.g., steel.

The attachment formations may be spaced along an entire length of the strap member at regular intervals. One of the attachment formations may be provided on the buckle member. The attachment formation may comprise a socket and spigot assembly. The attachment formation may include a socket body which defines the socket. The spigot may have an elongate spigot head, and the socket may define an elongate aperture through which the spigot head is configured to pass. The socket may define a cavity behind the aperture such that the spigot head may be rotated within the cavity once it has passed through the socket. The strap member may be provided with slots at spaced apart intervals where the attachment formations are to be placed. The slots may allow the spigot to pass through.

The socket body may define locating formations in the cavity, the locating formations configured to locate the spigot head in a rotated position. In the rotated position, the spigot head may not be withdrawn through the aperture. The locating formations may be angularly offset, e.g., 90°, relative to the aperture. Accordingly, the attachment formations may provide “twist and lock” functionality. The attachment point may be connected to the spigot head, e.g., via a shank or neck.

The invention extends to a buoyancy module assembly comprising:

-   -   a buoyancy module; and     -   at least one retention strap assembly, as defined above,         strapped to the buoyancy module.

The invention extends to a riser system comprising at least one riser joint having attached thereto a buoyancy module assembly as defined above. Plural riser joints may be connected together to form a riser string.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be further described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings:

FIG. 1 shows a three-dimensional view of a retention strap assembly for a buoyancy module in a riser system, in accordance with the invention;

FIG. 2 shows a three-dimensional view of a buckle member of the retention strap assembly of FIG. 1;

FIG. 3 shows a three-dimensional view of the buckle member of FIG. 2 with a tensioner rotated;

FIG. 4 shows a three-dimensional view of the buckle member of FIG. 3 from another angle;

FIG. 5 shows an enlarged three-dimensional view of the buckle member of FIG. 2 with some components removed;

FIG. 6 shows various schematic views of the buckle member of FIG. 2;

FIG. 7 shows a three-dimensional view of an attachment formation of the retention strap assembly of FIG. 1;

FIG. 8 shows an exploded three-dimensional view of the attachment formation of FIG. 7;

FIG. 9 shows various schematic views of the attachment formation of FIG. 7;

FIG. 10 shows a three-dimensional view of auxiliary equipment for use with the attachment formation of FIG. 7;

FIG. 11 shows another three-dimensional view of the auxiliary equipment of FIG. 10 and

FIG. 12 shows a three-dimensional view of the retention strap assembly of FIG. 1 installed on a buoyancy module.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT

The following description of the invention is provided as an enabling teaching of the invention. Those skilled in the relevant art will recognise that many changes can be made to the embodiment described, while still attaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be attained by selecting some of the features of the present invention without utilising other features. Accordingly, those skilled in the art will recognise that modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances, and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not a limitation thereof.

FIG. 1 shows a retention strap assembly 100 for a buoyancy module in a riser system. The retention strap assembly 100 has an elongate strap member 110, a buckle member 120, and a plurality of attachment formations 130, each of which is described in more detail below.

The strap member 110 comprises two elongate overlapping layers 112, 114 which are bonded (e.g., adhered or welded) together along some or much of their length. However, the layers 112, 114 are separate at least at their ends, where they loop around to form respective connection points 116 at each end to accommodate the buckle member 120, and at spaced intervals along their length, to accommodate the attachment formations 130. The strap member 110 is of a strong, deformable material, like reinforced rubber. The strap member 110 may be a continuous closed loop, adhered/welded together in certain sections to ensure that the attachment formations 130 are not able to shift. The strap member 110 may be reinforced with Kevlar. The strap member 110 is of a length to permit it to fit snugly around a buoyancy module (see further below) prior to tensioning, and tightly, with at least a frictional fit or a tensile fit, around the buoyancy module after tensioning.

FIGS. 2-6 illustrate the buckle member 120 in more detail. The buckle member 120 has a rectangular footprint and comprises a buckle frame 202 which is can either be formed of multiple individual components or a solid body as seen in this design interconnected by a plurality of transverse cylindrical crosspieces. The crosspieces are mechanically fastened to the side pieces by mechanical fasteners 206.1 (collectively referred to by reference numeral 206). The mechanical fasteners may be in the form of threaded bolts with a hex/Allen key socket and a triangular head which is configured to be countersunk into the buckle frame 202 or other surfaces. The bolts engage with matched threaded sockets defined in complemental parts.

A tensioner 204 is mounted inside the buckle frame 202. The tensioner 204, like the buckle frame 202, is formed of flat elongate side pieces interconnected by a plurality of cylindrical crosspieces. The tensioner 204 is rotatably mounted to the buckle frame 202 via mechanical fasteners 206.1. A centre crosspiece of the tensioner 204 may include a bearing assembly (not illustrated). The tensioner 204 acts, in use, as a class 1 lever (further explained below).

The buckle member 120 has two connection formations 210, 212. In this embodiment, the connection formations 210, 212 are provided by crosspieces. More specifically, a first connection formation 210 is at one end of the buckle frame 202 and is either fixed or able to pretention the strap, while a second connection formation 212 is provided on the tensioner 204 and is thus rotatable with the tensioner 204.

The first connection formation 210 is normally closed or fixed at both ends. However, mechanical fasteners 206.3 can be removed to loosen and remove the first connection formation 210 and for adjustment. The second connection formation 212 is fixed at one end but open/unfixed at the other, thus being supported cantilever-fashion. The second connection formation 212 can be secured to the buckle frame 202 by mechanical fastener 206.2, thereby fixing the whole tensioner 204 and rendering it immovable relative to the buckle frame 202.

The connection points 116 of the strap member 110, which are the looped ends of the strap member 110 in this example, are connectable to the corresponding connection formations 210, 212 of the buckle member 120. One of the connection points 116 is connectable to the first connection formation 210 by removing the mechanical fasteners 206.3 and threaded the first connection formation 210 through the looped connection point 116 and then re-fastening the connection formation 210 to the buckle frame 202. This connection may be semi-permanent in that it is not intended to be disconnected and connected frequently, but can be disconnected for servicing, maintenance, replacement, etc.

The other connection point 116 of the strap member 110 can be connected to the second connection formation simply by sliding the connection point 116 over the second connection formation 212 when the tensioner 204 is rotated relative to the buckle frame 202 (as in FIGS. 3-4). This connection is intended to be more removable than the other one, as this facilitates quicker coupling of the retention strap assembly 100 to the buoyancy module. To fix or release the strap member 110 from the second connection point 116, the mechanical fasteners 206.2 are secured or released, e.g., using a hex key driver.

The tensioner 204 defines a tool-receiving socket 220 into which a tool (e.g., a lever) can be inserted for extra levering advantage to tension the strap member 110 really tightly.

One of the attachment formations 130 is illustrated in more detail in FIGS. 7-9. Each attachment formation 130 comprises a socket assembly in the form of an socket body 302 and comprises a spigot 304. The strap member 110 has a plurality of slots 306 defined in its upper layer 112. The slots 306 are provided at spaced apart locations where the attachment formations 130 are intended to be placed. The slot 306 permits passage of the spigot 304 there-through, so that it can be inserted into or withdrawn from the socket body 302. The slot 306 also serves to locate the attachment formation 130 in place (at least temporarily) until it has been tensioned around the buoyancy module.

The composition of the attachment formation 130 is more clearly illustrated in FIGS. 8-9. The socket body 302 comprises a top section 310 and a complemental bottom section 312. The bottom section 312 is shaped and dimensioned to be received snugly within the top section 310 and to define a socket assembly which comprises a cavity 314 defined between the top and bottom sections 310, 312 and aperture 316 defined in the top section 310 to provide access to the underlying cavity 314. The aperture 316 is elongate and the cavity 314 is generally disc-shaped. Mechanical fasteners 318 are used to fasten the top and bottom sections 310, 312 together.

The spigot 304 which is matched to the socket body 302 and includes an elongate spigot head 324 which is configured to pass through the elongate aperture 316 when aligned. The spigot 304 may then be rotated with the spigot head 324 within circular cavity. At a rotated angle (e.g., 90°), the spigot 304 cannot be withdrawn because the head 324 cannot pass through the now misaligned aperture 316.

The spigot 304 also has a stem or shank 322 which is fixed to the head 324 for connection to auxiliary equipment (not illustrated). FIGS. 10-11 illustrate an example of the spigot 304 attached to a piece of auxiliary equipment which, in this example, is a cable clamp assembly 350. The type of auxiliary equipment itself is not germane to the invention, but the cable clamp assembly 350 can be quickly coupled to the retention strap assembly with a quick insert, twist, and lock action, by inserting the spigot 304 into the socket body 302. This quick coupling capability may be an advantage of the invention.

The socket body 302 defines locating formations. These locating formations are barely visible in FIG. 8 but more apparent in the sectional views of FIG. 9. The locations formations are in the form of an elongate recess 330 in an inner wall of the top section 312. The elongate recess is matched to the shape of the spigot head 324 and is a similar shape to the aperture 316. However, the elongate recess 330 is angularly offset by 90° relative to the aperture 316.

This cavity 314 has a bias member (e.g., a resilient spring) to help push the head 324 back up into the recess 330. Accordingly, when the spigot head 324 is inserted into the cavity 314 and rotated by 90°, the bias member urges the head 324 upwards into the recess 330. This ensures that there is always a force keeping the spigot 304 in place. This inhibits withdrawal of the spigot 304 from the socket body 302. To withdraw the spigot 304, a user would push it down, against the bias of the bias member, turn it by 90°, such that the head 324 aligns with the aperture 316 and remove it.

The attachment formation 130 in the buckle member 120 differs merely in that the top section is defined by the buckle frame 202, and the bottom section can be mounted thereto by mechanical fasteners 206.4.

The buckle member 120 and the attachment formations 130 are all of stainless steel to be resistant to the harsh marine environment in which they may operate.

The invention will be further described in use, with reference to FIG. 12. FIG. 12 illustrates a buoyancy module assembly 400 in accordance with the invention, which comprises a buoyancy module 402 and two retention strap assemblies 100. The retention strap assemblies 100 are accommodated within matched grooves 404 extending circumferentially around the buoyancy module 402. Each groove 404 is generally elongate to accommodate the strap member 110 and has an enlarged portion to accommodate the buckle member 120. The tension in the retention strap assemblies 100 and their location within the grooves 404 inhibits slippage.

First, the attachment formations 130 are fitted to the strap member 110 by an operator. This is done by spreading the layers 112, 114 in the region of the slot 306 and laterally inserted the attachment formation 130 between the layers 112, 114. The spigot shank 322 is fed through the slot 306 such that it projects outwardly. This also locates the attachment formation 130 in place until the retention strap assembly 100 has been tensioned.

Next, the strap member 110 is fitted by the operator to the buckle member 120 by removing the mechanical fasteners 206.3 to release the first connection formation 210 which is inserted into the connection point 116 of one end of the strap member 110. The first connection formation 210 is then re-inserted into the buckle frame 202 and fastened by means of the mechanical fasteners 206.3. This connection point 116 of the strap member 110 is then held firmly in place.

The other connection point 116 of the strap member 110 is then fitted to the tensioner 204. This is done by rotating the tensioner 204 to its open position (as shown in FIGS. 3-4) and then inserting the second connection formation 212 through the other connection point 116. The retention strap assembly 100 is then placed in the groove 404 (or it could have been placed in the groove 404 before the other connection point 116 was fitted to the second connection formation 212, as per the operator's preference), with the strap member 110 in the elongate part of the groove 404 and the buckle member 120 in the enlarged part of the groove 404.

The tensioner 204 is then rotated to its tensioned position (as shown in FIGS. 2 and 5). This rotation causes the strap member 110 to be tightened, with its ends being pulled together around the buoyancy member 402. This may require a lever or similar tool (not illustrated). This lever could be inserted into socket 220 (the fulcrum) and arranged to bear against a crosspiece (the load) opposite the second connection formation 212 of the tensioner, and then forcefully rotated (the effort). Either way, the tensioner 204 is rotated such that the second connection formation 212 aligns with the buckle frame 204 and then the mechanical fastener 206.5 is inserted and tightened to retain the tensioner 204—and the tensioned strap member 110—in place.

The attachment formations 130 are spaced along the length of the retention strap assembly 100, around a periphery of the buoyancy module 402, to be attached to appropriate auxiliary equipment.

The Applicant believes that the invention as exemplified as advantageous in that the retention strap assembly 100 can be tensioned using leverage, not threaded bolts. It is retained on the buoyancy module 402 using this tension and locating grooves 404, not mechanical fasteners. This renders coupling much quicker and does not cause as much wear and tear on the buoyancy module 402.

Attachment formations 130 are provided all around the retention strap assembly 100 and therefore all around the buoyancy module 402 for connection to whatever auxiliary equipment may be needed. The attachments formations 130 provide couple coupling spigot and socket assemblies 302, 304 which can be attached or detached with push-and-twist action. 

1. A retention strap assembly for a buoyancy module in a riser system, the retention strap assembly comprising: an elongate strap member comprising connection points at opposite ends, the strap member configured to wrap around the buoyancy module; a buckle member comprising connection formations configured to receive the connection points of the strap member, wherein the buckle member further comprises a tensioner configured to tension the strap member, the buckle member being configured to tension and hold the strap member around the buoyancy module; and a plurality of attachment formations spaced along a length of the strap member, each attachment formation comprising an attachment point configured for attachment to auxiliary riser equipment.
 2. A system as claimed in claim 1, wherein said connection points of the strap member may be provided by ends of the strap member being looped or folded over and wherein said strap member may comprise at least two overlapping layers.
 3. A system as claimed in claim 2, wherein said overlapping layers may comprise a single continuous strap, folded over itself, or plural strap parts arranged one above the other.
 4. A system as claimed in claim 1, as characterized in that said buckle member may comprise a buckle housing to which the tensioner is mounted.
 5. A system as claimed in claim 4, wherein said tensioner may be rotatably or pivotally mounted to the buckle housing and wherein said tensioner may be fixable relative to the buckle housing, e.g., using a mechanical fastener
 6. A system as claimed in claim 4, wherein said buckle member may comprise two connection formations wherein said connection formations may comprise crosspieces or transverse supports and/or a solid body (e.g. bars or rods) around which the strap member may be guided or wrapped wherein one connection formation may be provided on the buckle housing and the other connection formation may be provided on the tensioner.
 7. A system as claimed in claim 6, wherein said transverse supports may be removably attached to the buckle member and/or be removably attached by mechanical fasteners, e.g., nuts or screws and/or be removed to connect or disconnect the strap member, and then fastened in place so that the strap member cannot be removed without detaching the support members, in use.
 8. A system as claimed in claim 7, wherein neither the strap member nor the buckle member may be attached to the buoyancy module by mechanical fasteners.
 9. A system as claimed in claim 1, as characterized in that said tensioner may comprise a lever member wherein said lever member may be an over centre lever and include one of the connection formations and, via a levering action about its fulcrum, may be configured to tension the strap member when its connection point is connected to the connection formation of the lever member.
 10. A system as claimed in claim 9, wherein said lever member may embody a class 1 or class 2 lever and will be secondarily retained in place through the use of mechanical fastener, once in its tensioned position.
 11. A system as claimed in claim 1, as characterized in that said strap member may be of a polymer, e.g., plastic or rubber, manufactured to include Kevlar strands; said buckle member may be of metal, e.g., steel and said attachment formations may be of metal, e.g., steel.
 12. A system as claimed in claim 1, as characterized in that said attachment formations may be spaced along an entire length of the strap member at regular intervals and wherein one of the attachment formations may be provided on the buckle member.
 13. A system as claimed in claim 12, wherein said attachment formation may comprise a socket and spigot assembly and may include a socket body which defines the socket.
 14. A system as claimed in claim 13, as characterized in said spigot may have an elongate spigot head, and the socket may define an elongate aperture through which the spigot head is configured to pass and/or may define a cavity behind the aperture such that the spigot head may be rotated within the cavity once it has passed through the socket.
 15. A system as claimed in claim 12, wherein said strap member may be provided with slots at spaced apart intervals where the attachment formations are to be placed wherein said slots may allow the spigot to pass through.
 16. A system as claimed in claim 1, as characterized in that said socket body may define locating formations in the cavity, the locating formations configured to locate the spigot head in a rotated position wherein said spigot head may not be withdrawn through the aperture, in the rotated position.
 17. A system as claimed in claim 16, wherein said locating formations may be angularly offset, e.g., 90°, relative to the aperture and attachment formations may provide “twist and lock” functionality, accordingly.
 18. A system as claimed in claim 1, as characterized in that said attachment point may be connected to the spigot head, e.g., via a shank or neck.
 19. A system as claimed in claim 1, as characterized in the extension of said invention to a buoyancy module assembly comprising a buoyancy module; and at least one retention strap assembly, as defined above, strapped to the buoyancy module and/or the extension of said invention to a riser system comprising at least one riser joint having attached thereto a buoyancy module assembly as defined above.
 20. A system as claimed in claim 19, wherein said plural riser joints may be connected together to form a riser string. 